Details might be hazy at the moment, but Apple is attempting to patent a remote kill switch that can disable your device if it detects unauthorized activities.

Engadget - While the patent mostly sounds targeted at opt-in security software and would simply send you an alert or perform a remote wipe if your phone were stolen or hacked, jailbreaking and unlocking are also explicitly mentioned as the marks of an unauthorized user, and one line mentions that cellular carriers could shut down or cripple a device when such a user is detected.